Very agressive front end braking problem on tony kart 401rr (Rotax DD2)

hello, i´ve been racing in the DD2 series for over 3 years now and decided this would be a great time to upgrade my CRG chassis (has seen better days), so i bought a tony kart 401rr, brand new and everything, first day at testing i noticed this agressive vibration towards the front end of the kart, it usually happens at the edge of locking up the tyres at high speed braking zones, thing that in my experience tends to happen a lot in karting but it doesn´t punish you or the kart like this, front end vibration was so violent that my steering rod bent up without even crashing, me and my mechanic don´t think its a normal thing and we don´t know how to fix it, the issue tends to be less dramatic when you switch the bias towards the back, but this way you cant really brake at the limit, this issue is really messing up my driving. (i´d like to emphasize that the kart is brand new)

would really appreciate some help :slight_smile:

I drove the model R model year ago and it was the same. The tony front brake is wayyyy to sensitive, specially after coming from crg. You have to adapt for this, i hear it from many tony drivers. You can try to use some aftermarket softer pats, they will help a bit. But this was also the reason for me to drop the tony and switch to birel, which suits also more to my driving style

I don’t think the “problem” comes form the brakes, I basically drive both the tonykart and Formula K (IPK) full time and I imagine the formula K is closer to crg, generally I think the tonykart chassis is softer in the front to back axis while being harder side to side, this only shows when you have front brakes because it loads the front way more than other chassis and gives you this one sharp turn in and basically nothing after because it’s not soft enough side to side to keep the wheel up, although this seems like a downside of you can utilize it and turn the kart as much as you can in the entry you’ll find yourself with a much straighter trajectory in the exit, keep a lot of front bias, don’t brake as hard and let the downshift brake the rears

Assuming the components and alignment are good, it’s not unusual for a kart to behave this way if you have excessive front bias.

You won’t quite get to the same kind behavior as a car, the steering on the kart will pull, drag and dart quite a bit if you’ve gone over on the front bias.

i don´t think its a braking bias issue, i balanced the brakes more towards the back and the effect its still there, i´ve been wondering if its a natural effect on this sort of chassis but i really find it strange that its THAT violent of a vibration.

I’d check everything, play in tie rods, if hubs are properly tighten, bleed everything once again.

Also try play around with the brake rod at the pedal, you could lower it to middle/lowest hole for lest responsive braking. You get more leverage the higher the rod is